Nitrous Oxide Emissions from Agricultural Soils in Wisconsin1
- L. L. Goodroad,
- D. R. Keeney and
- L. A. Peterson2
Nitrous oxide (N2O) emissions from field plots on a Plano silt loam soil (Typic Argiudolls) at the University of Wisconsin-Arlington Experimental Farm were measured from the summer of 1979 through autumn 1981. The treatments, selected to give a wide variation in management, were: reduced tillage (till-plant) corn (Zea mays L.); rye (Secale sativa L.) cover; long-term stable pH (pH 4.7, 5.1, and 6.7); oat (Avena sativa L.) straw residue; alfalfa (Medicago sativa L.) residue; and dairy manure and sewage sludge amendments. Nitrous oxide fluxes, measured by a static chamber technique, were greatest with the manure-amended and reduced tillage treatments, and were greater in 1980 than in 1979 or 1981. Highest rates of N2O emission were often observed at soil thaw. No significant effects on the emission rate or amount of N2O evolved due to soil pH was observed. Surface N2O fluxes were characterized by a high degree of variation. Mean N2O-N emission rates calculated from measured N2O-N emission rates during annual sampling periods ranged from 1.6 to 38.7 ng N2O-N m−2 s−1 for the treatments sampled. Coefficients of variation for these means ranged from 50% to > 200% and from 100 to 350% for spatial and temporal variability, respectively. Total N2O emissions (kg N2O-N ha−1) for 1980, the most complete sampling period, were: reduced tillage corn, 3.5 in the row and 6.3 between the row; sludge, 1.6; manure, 6.1; alfalfa, 3.2; rye, 1.6; straw, 2.2; pH 4.7, 1.5; pH 5.1, 0.9; pH 6.7, 1.0. These values are similar to those reported in the literature from comparable agricultural sites.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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